1. Field of the Invention
The present invention relates generally to orthopedic devices for the stabilization and control of a human knee joint that has been injured. More particularly, the invention relates to an orthopedic knee brace including a joint assembly having improved strength and stability characteristics and also an automatic lock mechanism which enables a wearer to releaseably lock the joint assembly in an effort to prevent the unintentional rotation of the joint assembly.
2. Description of the Related Art
Orthopedic knee braces are commonly worn by patients after surgery for treatment of an injury to the knee joint. Knee braces generally serve dual purposes: first, the brace stabilizes the joint in order to control its lateral movement. Second, they limit joint flexion and/or extension in an adjustable and controllable manner to prevent recurrence of injury to the knee. For example, an overall increase of injuries to the knee joint in professional and amateur athletics has given cause for the increased use of orthopedic knee braces to help facilitate the quick rehabilitation of the knee joint.
A knee brace of the initially mentioned type is disclosed in one of the present inventors U.S. Pat. No. 5,259,832, which discloses a multi-axis controlled knee brace utilizing a four bar joint mechanism including a femoral bar and a tibial bar, each of which has two pre-drilled holes for attachment of an inner lap-style link and an outer link that secure the tibial bar to the femoral bar. The joint of this brace, however, lacks a means to easily immobilize and subsequently release the joint. Furthermore, it has been found that a stronger joint is needed in cases where the joint undergoes torsional stress.
The use of orthopedic knee braces having locking members has become conventional within the prior art. Such an arrangement generally permit the wearer to releasably lock the hinge or joint of the knee brace in one or several angular positions to thereby restrict the degree of rotation of the brace. However, certain shortcomings have been encountered with regard to the use of the conventional locking members for orthopedic knee braces.
For example, U.S. Pat. No. 5,409,449 to Nebolon discloses an orthopedic knee brace having a rotatable hinge including two rotatably attached members and a detent mechanism for automatically and releasably locking the hinge in a fixed position of rotation. The detent mechanism includes an indentation formed in the attached end of one attached member and a block pivotally mounted on the other attached member. The block includes a locking projection that is biased toward the indentation and cooperates therewith to provide three positions of operation: a locked position, a release position, and an activated position. In the locked position, the locking projection fittingly engages the indentation, thereby substantially preventing rotation of the hinge. The release position displaces the locking projection a radial distance away from the indentation, thereby permitting the hinge to rotate freely. In the activated position, the block disengages the indentation and maintains an angular distance to enable automatic repositioning of the hinge assembly to the locked position whenever the locking projection and indentation angularly realign. While this design allows for the wearer to releasably lock the hinge, it does not provide for an effortlessness and simplistic locking and releasing of the knee joint since it requires cooperation between numerous parts to effectuate the locking and unlocking of the hinge.
Accordingly, there is still a need for a joint assembly for an orthopedic knee brace that provides improved strength and stability characteristics, especially when a lateral bending torque is applied to the joint assembly. There also is a need for a lock mechanism for use in an orthopedic knee brace that allows the wearer to manually and releasably lock the joint assembly in a simple and effective manner to prevent the accidental or unintentional rotation of the knee brace.
In view of the foregoing, it is an object of the present invention to provide a joint assembly for use with an orthopedic knee brace having enhanced strength characteristics as well as having the ability to provide enhanced kinematics to the wearer.
It is another object of the present invention to provide a lock mechanism for use with an orthopedic knee brace that can quickly and releaseably lock the joint assembly to prevent the unintentional rotation of the knee brace.
These and other objects and characteristics of the present invention are achieved in accordance with a preferred embodiment, which provides a joint assembly for an orthopedic knee brace by which lateral side and medial side femoral links are pivotally connected to lateral side and medial side tibial links respectively, and also a lock mechanism having the ability to releasably lock the joint assembly of the knee brace in a quick and efficient manner. The lock mechanism is an advantageous feature since it prevents the unintentional rotation of the knee brace. Moreover, the joint assembly is advantageous since it provides greater flexibility and range of motion to the wearer.
An exemplary embodiment of the joint assembly generally exhibits the same kinematics as the four bar hinge described in the above-mentioned U.S. Pat. No. 5,259,832. The joint assembly comprises a femoral bar and a tibial bar, each having pre-drilled holes for attachment to upper and lower side plates. To provide for a sturdy design, both the femoral bar and tibial bar are in the form of upper struts and lower struts which can be formed of aluminum, titanium, or fiber and resin composites. A knee pad support comprising a generally circular shaped plastic condial attached to a condial link is configured to rest on the lateral and medial sides of the knee joint of the wearer for maintaining proper positioning of the joint assembly and for stabilizing the knee joint of the wearer. Moreover, a latch cap is fixedly connected to cap link to provide lateral protection to the joint assembly.
In an effort to enhance the strength and stability of the joint assembly, particularly when a lateral bending torque is applied thereto, an improved clevis-type joint is employed. The clevis-type joint includes a pair of outer linkages comprising a cap link, a condial link, and an inner link disposed between a pair of upper and lower side plates to fixedly attach the femoral bar to the tibial bar and thereby produce a glide and roll motion during extension and flexion of the wearer""s leg.
The joint assembly is further provided with a mechanism for releaseably locking the joint mechanism in a substantially 180xc2x0 position. The lock mechanism includes a release lever for slidingly placing the joint assembly in a lock or a release mode, and a pivotal trigger that effectively locks and releases the joint assembly while in either the lock or the release mode. The release lever is mounted for sliding movement between the lower side plates and has an elongated L-shaped body portion terminating into a tip portion at a distal end thereof, and at least two projecting pins perpendicularly extending from its body portion that are designed to slidingly move within laterally-placed groove portions of the lower side plates. The release lever further includes a handle portion designed to be engaged by a thumb or finger of the wearer to place the release mechanism into a first position in which the joint assembly is in a lock mode, and a second position in which the joint assembly is placed into a release mode.
The trigger is mounted for pivotal movement between the upper side plates and includes an elongated body portion, at least one projecting pin extending perpendicularly from the body portion and provides for the pivotal movement of the trigger, and also a hook portion located at a basal end of the trigger. The trigger also includes a handle portion designed to be engaged by the thumb or finger of the wearer to effectively lock and unlock the joint mechanism. The joint assembly is locked in a substantially 180xc2x0 position by pivoting the trigger in a manner such that the hook portion of the trigger engages the hook portion on the lower side plates and tibial link. The joint assembly is unlocked by manipulating the handle portion of the trigger in a manner that disengages the hook portion of the trigger from the hook portions of the lower side plates and tibial link. Further, a biasing element, such as a coil spring, is disposed between a back surface end of the trigger and the femoral bar to bias the trigger into the respective lock and unlock positions.
The lock mechanism is provided with a unique safety feature that offers a wearer additional protection for cases in which the trigger is accidentally or intentionally unlatched while the joint assembly is in a locked mode. In such cases in which the release mechanism is maintained in the locked position, but the joint assembly is caused to rotate due to the unlatching of the trigger, the joint assembly will nonetheless automatically relock if the joint mechanism is rotated to a fully extended or substantially 180xc2x0 position.
In operation, the joint assembly may be effortlessly and quickly unlocked by the wearer by sliding the release mechanism forward until the distal end of the release mechanism abuts the hook portion on the tibial link. Accordingly, because the distal end of the release mechanism abuts the hook portions of the tibial link, the hook portion of the trigger is prevented from interlocking with hook portions of the lower side plates and tibial link, thereby allowing the joint assembly to freely rotate.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the detailed drawings which show, for purposes of illustration only, a single preferred embodiment of the present invention.